Light emitting flat panel devices have previously been proposed:
A. A device which has light scattering semi-transparent flat panel with fluorescent lamp at the backward or sideward of the panel has been used for mono-color and/or multi-color LCD devices. In this case, there are many problems on:
a. Thinness of the device is limited because there is a limitation to decrease diameter of fluorescent lamp.
b. Unsuitable for portable equipment because consumption of electric power of a fluorescent lamp is comparably large.
c. When the device is used for color display, it requires three kind of numerous color filters for each image element, because the fluorescent lamp emits mono-color. It means increase of manufacturing cost. In addition, since the color filter absorb much light power, intensity of fluorescent lamp must be increased, which means increase of electric power consumption.
B. Among other light emitting flat panel devices, there is a one using many side leak type optical fibers (Japanese Patent Application No. 86-68742, Japanese Patent Publication No.94-64272, Aug. 22, 1994). In this case, it requires complicated process as explained below, which invites increase of cost.
a. It needs a precision process which arranges many optical fibers at the very right position accurately.
b. It needs a precision process to make small holes of detailed dimensions and shapes on the accurate position on the side of each optical fiber.
c. It needs a sophisticated assembling process to bundle one end or both ends of optical fibers in group by color, which transport color light from each light source respectively.